CAT1026WI-45-GT3 ON Semiconductor, CAT1026WI-45-GT3 Datasheet - Page 7

• Manufacturer Part Number: CAT1026WI-45-GT3
• Description: IC SUPERVISOR CPU 2K EEPR 8SOIC
• Manufacturer: ON Semiconductor
• Type: Multi-Voltage Supervisorr

Specifications of CAT1026WI-45-GT3

• Number Of Voltages Monitored: 2
• Output: Open Drain or Open Collector
• Reset: Active High/Active Low
• Reset Timeout: 130 ms Minimum
• Voltage - Threshold: 4.5V, Adj
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

DEVICE OPERATION
Reset Controller Description
The CAT1026 and CAT1027 precision RESET
controllers ensure correct system operation during
brownout and power up/down conditions. They are
configured with open drain RESET outputs.
During power-up, the RESET outputs remain active
until V
driving the outputs for approximately 200 ms (t
after reaching V
device will cease to drive the reset outputs. At this
point the reset outputs will be pulled up or down by
their respective pull up/down resistors.
During power-down, the RESET outputs will be active
when V
valid so long as V
designed to ignore the fast negative going V
ent pulses (glitches).
Reset output timing is shown in Figure 1.
Manual Reset Capability
The RESET
manual reset input. The input is edge triggered; that
is, the RESET
detecting a high to low transition.
When RESET
200 ms timer will begin to time the reset interval. If
external reset is shorter than 200 ms, Reset outputs
will remain active at least 200 ms.
Monitoring Two Voltages
The CAT1026 and CAT1027 feature a second voltage
sensor, V
output low whenever the input voltage is below
1.25 V. The auxiliary voltage monitor timing is shown
in Figure 2.
By using an external resistor divider the sense
circuitry can be set to monitor a second supply in the
system. The circuit shown in Figure 3 provides an
externally adjustable threshold voltage, V
monitor the auxiliary voltage. The low leakage current
at V
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Characteristics subject to change without notice
SENSE
¯¯¯¯¯¯ pin can operate as reset output and
CC
¯¯¯¯¯¯ I/O is driven to the active state, the
¯¯¯¯¯¯ input will initiate a reset timeout after
CC
reaches the V
SENSE
allows the use of large value resistors, to
falls below V
, which drives the open drain V
TH
. After the t
CC
is >1.0 V (V
TH
TH
. The RESET
threshold and will continue
PURST
¯¯¯¯¯¯ output will be
RVALID
timeout interval, the
). The device is
CC
TH_ADJ
transi-
PURST
LOW
to
)
7
reduce the system power consumption. The V
output can be externally connected to the RESET
output to generate a reset condition when either of the
supplies is invalid. In other applications, V
can be used to interrupt the system controller for an
impending power failure notification.
Data Protection
The CAT1026 and CAT1027 devices have been desig-
ned to solve many of the data corruption issues that
have long been associated with serial EEPROMs. Data
corruption occurs when incorrect data is stored in a
memory location which is assumed to hold correct data.
Whenever the device is in a Reset condition, the
embedded EEPROM is disabled for all operations,
including write operations. If the Reset output(s) are
active, in progress communications to the EEPROM
are aborted and no new communications are allowed.
In this condition an internal write cycle to the memory
can not be started, but an in progress internal non-
volatile memory write cycle can not be aborted. An
internal write cycle initiated before the Reset condition
can be successfully finished if there is enough time
(5 ms) before V
In addition, to avoid data corruption due to the loss of
power supply voltage during the memory internal write
operation, the system controller should monitor the
unregulated DC power. Using the second voltage
sensor, V
supply, the CAT1026 and CAT1027 signals an impen-
ding power failure by setting V
Watchdog Timer
The Watchdog Timer provides an independent protec-
tion for microcontrollers. During a system failure, the
CAT1027 device will provide a reset signal after a
time-out interval of 1.6 seconds for a lack of activity.
CAT1027 is designed with the Watchdog timer feature
on the WDI pin. If WDI does not toggle within 1.6
second intervals, the reset condition will be generated
on reset output. The watchdog timer is cleared by any
transition on monitored line.
As long as reset signal is asserted, the watchdog
timer will not count and will stay cleared.
SENSE
CC
, to monitor an unregulated power
reaches the minimum value of 2 V.
CAT1026, CAT1027
LOW
low.
Doc. No. MD-3010 Rev. P
LOW
signal
LOW